.. py:function:: state(original[, change1=change1, changeN=changeN])
A `ContextDecorator` that takes `original` and applies the changes
sent as parameters and modifies `original` with these
parameters. Upon completion it will restore `original` to the
state it was before being called. Parameters can also have the
marker value of :py:class:`forget` to temporary remove this name
when :py:func:`state` is in effect.